In order to regenerate the cutaneous barrier of the skin, it is known, in particular from document FR-A-1 350 038, that is it desirable to treat the skin with regenerative cosmetic compositions containing an active principle that is rich in lipids, in particular polar lipids extracted from the flesh of nacreous mollusks, in particular from oyster flesh. The extraction processing is complex since it is necessary to begin by grinding the flesh, either after drying it, or else after dehydrating it. The processing is therefore expensive. In addition, the flesh of nacreous mollusks is suitable for food applications for humans or animals, such that the raw material is itself of non-negligible cost.